1. Field of the Invention
The present invention relates to an image storage method and apparatus for an image database used to search for a desired image from a plurality of images.
2. Description of the Related Art
A number of image databases for searching for desired images from a large amount of image data have been proposed. Many of these image databases are roughly classified into:
*a method which relates non-image information such as a keyword or photographing date to each image and searches for an image on the basis of this information; and
*a method which searches for an image on the basis of features (e.g., luminancexe2x80xa2color difference information, image frequency, and histogram) of each image.
In both methods, information for search and image data are generally separately managed. For example, data for search is managed by one file or relational database and used as an object of search. The file name of image data corresponding to a search result is obtained, and on the basis of this file name the image data is accessed and displayed. This method is employed because image data generally has a large volume and hence can be managed more efficiently when managed separately from search data.
Individual image data is managed in a file system, and the following two methods are possible as the method of management. The first method is to manage all image data as one directory. The second method is to segment image data into several groups in units of a plurality of images and manage these groups by classifying them into directories. For example, image data are classified into directories in accordance with the contents of images such as xe2x80x9canimalxe2x80x9d and xe2x80x9cflowerxe2x80x9d.
In either of the above first and second methods, however, when a plurality of images obtained from the result of search using a search key or the like are to be simultaneously displayed, image access requires an extremely long time if the number of images is very large.
The first method can easily manage images. However, if the number of images is extremely large, a huge time is necessary to obtain only directory information. In the second method, it is necessary to always accurately maintain the correspondence between image files and directories, and this complicates management such as movement of image files.
Also, registration of images into an image database is usually automated. For example, images are successively read from a continuous film by a scanner apparatus and registered in a database. Alternatively, motion images are continuously input as still images from a video tape or the like and registered in a database. These methods have been put into practical use.
In taking photographs, however, the same scene is often photographed continuously. In the case of videotaping, the same image continues for several seconds in many instances. In either case, a number of images of exactly the same scene, or very similar scenes, are successively registered in a database if the automatic registration as described above is performed. Furthermore, images which the user does not require, e.g., commercial images, are sometimes registered between necessary images.
It is desirable to eliminate these images from a database. However, as described previously, general image databases require a long time to access images and a complicated way to manage directories and the like. Therefore, even deleting a single image requires a long time.
The present invention has been made in consideration of the above situation, and has as its object to allow high-speed access to image data and simple management of image data.
It is another object of the present invention to allow high-speed access to image data and simple management of image data, and delete image data from an image database at high speed.
It is still another object of the present invention to reliably erase the body of image data as a delete target and thereby reduce the data size of an image database.
It is still another object of the present invention to allow the restoration of even a once deleted image when it is again required.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.